1. Field of the Invention
The present invention is directed to the field of optical scanning and more specifically to the area of gyroscopically mounted missile seeker assemblies and other optical telescope applications.
2. Description of the Prior Art
In the last several years, it has been found that the most efficient data collection pattern for scanning a field of view with a gyro-stabilized target seeker in a missile is the "rosette" scan pattern. The "rosette" scan pattern and prior art assemblies are discussed in U.S. Pat. Nos. 4,009,393; 4,030,807; and 4,039,246, the texts of which are incorporated herein by reference. In each of the aforementioned patents, the "rosette" scan pattern is achieved in a cassegrain type telescope configuration by effecting counter-rotation of two separate, slightly canted, scanning elements and effecting counter-rotation by employing a separate rotational drive motor for each scanning element.
Although the prior art attempts described above appear to give a sound theoretical approach to achieving the "rosette" scan pattern, the actual construction of such devices has been found to present critical imbalance problems and phase instability. Other problems occur in attempting to incorporate the number of drive motors specified in the prior art patents into the severely limited space provided in missile environments.